Litter box



FIG. 1 is a front perspective view showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view thereof; and,

FIG. 4 is a right side elevational view thereof.

A bottom view of the litter box is not provided, as it is not part of the design sought to be patented. 

The ornamental design for a litter box, as shown and described. 